The present invention relates to the general field of guide vanes for a compressor or a turbine of a turbine engine such as a turbojet, an airplane turboprop, a steam turbine, or a compressor.
More precisely, the invention relates to damping the vibration modes to which the vanes of a diffuser are subjected in operation.
In a turbine engine compressor, the compressor is made up of a plurality of compression stages, each made up of an annular row of blades mounted on a rotor shaft and a diffuser made up of a plurality of vanes mounted radially on an outer annular casing of the turbine engine.
A compressor diffuser is generally sectorized, i.e. it is made up of a plurality of angular sectors placed end to end around the longitudinal axis of the compressor. Typically, each diffuser sector comprises an inner shroud and an outer shroud that are arranged axially one inside the other, together with one or more vanes extending radially between the shrouds and connected thereto via their radial ends. At each of their radial ends, the outer shrouds of the diffuser sectors have means for mounting the sectors on the outer casing of the turbine engine.
In operation, an angular diffuser sector is subjected to high levels of mechanical stress, both static and in vibration. These mechanical stresses are withstood essentially by the leading-edge and trailing-edge zones of the vanes that are connected to the outer shroud of the diffuser sector. Since these connection zones are particularly thin, there is a risk that the resulting mechanical stresses damage or even destroy the leading and trailing edges of the vanes.
In order to avoid that drawback, various solutions have been envisaged. By way of example, mention may be made of patent applications FR 10/54849 and FR 10/54851 filed on Jun. 18, 2010, which make provision for housing a damper- or abutment-forming fitting in a cavity formed in the outer shroud of the angular diffuser sector so as to reduce the mechanical stresses to which the vane is subjected in operation. Also known is Document FR 2 896 548, which describes a set of diffusers in which one of the assembly tabs is connected to the outer shroud in a zone that is axially spaced away from the connection zone of the leading or trailing edges of the vanes with the outer shroud.
Although effective, those solutions present the disadvantage of leading to premature wear of the contact parts, which can lead to the assembly losing its damping ability.